Collapsible tire building core



July 21, 1931. F. D. MASON I COLLAPSIBLE TIRE BUILDING CORE 2Sheets-Sheet 1 Filed June 4. 1929 July 21, 1931. F. D. MASON COLLAPSIBLETIRE BUILDING CORE Filed June 4. 1929 2 Sheets-Sheet 2 amen Joe PatentedJuly 21, 1931 U STATES a FREEMAN D. MASON, OF AKRON, OHIO, ASSIGNOR TOTHE BRIDGWATER MACHINE COMPANY, OF AKRON, OHIO, A CORPORATION OF OHIOCOLLAPSIBLE TIRE BUILDING CORE Application filed June 4, 1929. SerialNo. 368,413.

8 This invention relates to collapsible tire building forms andespecially core forms of the type in which certain of the segments arehinged upon a rotary chuck or spider and adapted to be swung from avertical to a 1 Such cores heretofore have commonly been of all-steelconstruction and breakage of the hinge members has been a commonoccurrence,espec1ally 1n the larger sizes, on account of the high momentof inertia developed when 15?, the operator, oftenviolently, turns thestructure into its horizontal position and it is sud denly arrestedbythe hinge stops. This high inertia factor is also encountered in theexpanding and collapsing movements of the segjments with reference toeach other in this and other types of articulated cores.

' The object of my invention is to reduce this breakage and at the sametime provide a highly durable core construction. I have 'found that bymaking the cores with body portions of a light metal "such as aluminumor magnesium or an alloy in which such metal is the principalconstituent, while the tongue portions carrying the hinge members aremade of a heavier and stronger metal such as steel, breakage ispractically eliminated and the core has the advantages of an all-steelconstruction without its draw-backs.

Of the accompanying drawings: Fig. 1 is an elevationof a collapsiblecore,

including the chuck or spider, embodying my I invention in its preferredform, the same be ing shown in assembled or tire-receiving position.

Fig. 2 is a section on line 22 of Fig, 1. Fig. 3 is an elevation, fromthe right of Fig. 1, of the core in partially collapsed condition. Fig;1 is an elevation of the segments of a steel base ring for the core,light metal core segments molded thereon being shown in broken lines,this figure illustrating a step in the process of making the core.

Fig. 5 is a cross-section of one of the segments of a modified form ofcore.

' Referringto the drawings, the finished assembly, shown in Figs. 1, 2and 3, comprises a hub member 10 secured upon the end of a rotatable,horizontal shaft 11; a core segment 12 hinged at 18,13 on a horizontalaxis A A transverse to the shaft 11, to the lower part of the hub member10; a core segment 14 hinged to one end of the segment 12 at 15, on anoblique axis such as to cause the segment 14 to swing obliquely downwardfrom the plane of the segment 12 when the segment 1 1,

with the segment 12 in its horizontal position of Fig. 3, is swung outof a. tire mounted upon them; a segment 16 hinged to the other end ofthe segment. 12 at 17 on an oblique axis such as to cause the segment 16to rise from the plane of the segment 12 in being swung" out of thetire; and a key segment 18 secured upon a pair of supporting rods 19, 19slidably mounted in apertured guide brackets 20, 20, 21, 21 formed onthe plate 10, the key seg ment being connected to the plate 10 by anover-center toggle 22 having a handle 23, for raising the key segment 18into its core-completing position between the segments 14, 16 and forlowering it out of the tire to permit the other segments, and the tirethereon, to be swung down to horizontal position about the axis 13, inwhich position they are stopped by shoulders 18*, 13 on the base ofcore-segment 12 abutting the ears 13*, 13 of the plate 10, as shownclearly in Fig. 3,the stoppage frequently being so violent. because ofthe unbalanced weight and inertia of the structure, as to cause breakageof the hinge portions of the core segments when the latter areofallsteel construction as heretofore made.

Each of the core segments 12, 14, 16 and 18 comprises a'cast steel baseor tongue portion such as the portion 24, Fig. 2, adapted to withstandthe wearing action of trimming and other tools, and a body portion suchas the portion 25, Fig. 2, of a light and strong metal such as analuminum alloy, cast upon the base portion and interlocked againstmovement in any direction with relation thereto.

The casting of aluminum alloys upon and in interlocked relation to steelbodies heretofore has been difiicult and in many instancesunsatisfactory, because of breakage of the alloy resulting fromshrinkage thereof, es pecially in bodies of such size as a tire-buildmgcore.

I have overcome the difiicult-ies and disadvantages in casting analuminum alloy upon a base ring structure to form the core herein shown,and have provided for an accurate shapin of the core segments, by theprocedure v- 11.1 is in part illustrated in Fig. 4.

A base ring is first cast, of steel, with interlocking means on itsouter periphery such as the ci'cumferentially and axially interlocl-ning spaced lugs 26, 26, each of which is formed with lateral flanges 27,27 (Figs. 2 and 3) to provide a radial interlock. The base ring also ispreferably cast with undercut groove 28 extending entirely around itscircumference and of greater depth than the height of the lugs 26, toprovide additional axial and radial interlock. is also cast with hingelugs 29, 29 (Fig. 4).

The ring is then roughly machined, after which it is cut through aplurality ofpositions, as at 30, 30 (Fig. 4) 0 pro *ide a plurality ofsegments, 31, 32, 3o, 34. ments are then heated to approximately themelting temperature of the aluminum alloy to be used for the bodies or"the core sections and are supported in true circular form, the cutsproviding gaps between them, and while they are so held they areassociated with a suitable sand core and a complete ring of aluminumalloy iscast upon them and allowed to cool and shrink. In shrinking thealuminum alloy causes the gaps between the steel base sections to close,the sand being oromptly removed from the said gaps'after th metalpoured, and because of the comparatively short length of the sectionsthe differential of shrinkage between the alloy body structure and thesteel base structure is not cumulative throughout the circumference ofthe structure in the matter of creating breaki stresses in the alloy butonly throughout length of the ind' 'dual segments, so such differentialis not effective to break tl alloy structure. The fact that t ing lugs26 are circuin eren'i apart instead of being continuous also contributesto the avoidance of shrinkage cracks and breakage in service of thealloy body at its junction with. the tongue, although I do not whollyrestrict myself to this feature.

The annular steel and alloy structure is then machined to final form,with permissi- The ring These seg bly the exception of the hinge lugsand other attachment elements, after which it is out through at 36, 37,38, 39 to provide individual segments, which are then finished andmounted upon the spider.

The alloy ring is preferably cast with a cavity in each segmentalportion by the use of sand cores, and with internal, transversepartitions 40, 41, 42, 43 at the positions of the final cuts, to providestrength at the ends of the sections and to provide a firm support forinterlocking steel end plates such as the plates 44, 44 and 45, 45, asto the key segment 18 and the adjacent hinged segments 14 and 16. Theplates 44 are secured by screws to the respective segments 14 and 16 andthe plates 45 are secured to the key segment 18. Each of the plates 45is provided with a key 46 running in a radial key-way 47 formed in theend of the adjacent hinged segment and the plates 44', 45 of eachpair'are formed with complemental bevels at 48 to interlock the segmentstogether.

I am aware that it has been proposed to use aluminum as the material fortire vulcanizing cores and molds for the benefit of its greater heatconductivity and the greater facility in lifting and transportationafforded by its lightness, and I do not claim such practice broadly. Asomewhat different problem is encountered and solved by my present in;-vention in that the collapsible cores or' forms to which it relates arepermanentlymounted on rotary supports and not subjected to heat,

so that mere weight is a secondary consideration and thermalconductivity is unimportant, but durability and the overcoming ofbreakage in. a hinged structure are highly important factors not presentin the prior situations and the complete substitution of aluminum forsteel would be unsatisfactory as a solution for this problem.

By making a partial substitution and providing a composite structure asdescribed, not only are the requirements of this particular situationfully met, but a somewhat unlockedfor benefit arises in the way of ashifting of the centers of gravity and centers of inertia of the movingmasses toward the hinge axis or axes as compared with the all-steelconstruction heretofore prevalent in these permanently-mounted hingedcores.

Referring to Fig. 1 and considering the two upright core-segments 14,16, together with their tongue segments 32, 34, it may be assumed thatthe center of gravity of the segments 16, for example, liesapproximately midway of its horizontal boundary planes B, B or on theline B In like manner, the center of gravity of the steel tongue section(neglecting its hinge lug) may be assumed to lie approximately midway ofits boundary planes C, C or on the line G which lies considerably belowor nearer to the hinge axis AA than does the center line for thealuminum segment 16. If segment 16 were infinitely heavy as comparedwith seg ment 34, the center of gravity of the combined segments wouldlie on the line 13 and if it were infinitely light, said center wouldlie on the line C When both the body and tongue of the segment are madeof steel, as

to the hinge axis AA than where both suitable aluminum alloy are castand tongue and body are made of steel. Since the core structure issymmetrical on opposite sides of its vertical axis, the combined centerof gravity of the two composite segments 141, 32 and 16, 3 1 would be atthe intersection of said vertical axis with the line D.

These centers of gravity are also the centers of inertia of the movingmasses hinging about the axis AA, and a like demonstration applies tothose which are mostly negative in gravity as to said axis such as thecomposite body and tongue segment 12, 33, whose center of gravity andinertia may be assumed to lie at the intersection of the vertical coreaxis'with a line G lying about midway of the line E which is half-waybetween the boundary planes E and E of the body 12, and F which ishalf-way between the boundary planes F and F.

I thereby obtain not only the advantages of lightness and long wear byemploying the described composite core structure, but also a hingedcollapsible core or form involving much smaller inertia forces actingcloser to the hinge 13, 1.3 when the swing-out segments are turnedthereon, and closer to the hinges 15, 17 when the segments 14 and 16 areturned on said hinges, thus greatly reducing the amount of breakageexperienced in the use of such cores or forms.

In the modification shown in Fig. 5 a ring of steel is cast with anannular flange or web 51 extending from the middle of its outerperiphery and two annular shells 52, 52 of a secured on the respectivesides of the web as by bolts such as the bolt 53 extending withsubstantial. clearance through holes such as the hole 54L formed in theweb. The steel ring and the alloy shells are formed to interlock witheach other at the outer periphery of the structure against outwardrelative movement of the shells, as at 55, 55, and to interlock witheach other at the inner peripheries of the shells against inwardrelative movement of the shells, as at 56, 56. Each shell is preferablyformed with an apertured boss 52 at each bolt, the boss being of suchlength as to permit a slight springing of the shell by the bolt topermit the latter to tighten the shells and the steel ring in theirinterlocked relation radially of the structure but to abut the web 51 toprevent an excessive springing of the shells.

The shells and the ring also are preferably interlocked against relativecircumferential movement, as by means of dowels such as the dowel 57,mounted in holes which are bored after the shells and base ring areassembled and are plugged, at the ends of the dowels, after the dowelshave been inserted. Thus, a completely interlocked, as well as a tightstructure is provided.

The steel ring and the alloy shells preferably are machined before beingassembled, and after the structure is assembled in annular form it isout into individual core seg ments and the segments are then completedby suitable plugging or capping of their ends and mounted upon thespider. though the light-metal body members 52, 52 are or may bedetachable from the tongue portion 50 as described, in this modificationas Well as in the main form previously described, the body and tongueportions are permanently associated in each segment, in the sense thatthey remain united when the segments are moved to collapse or expand thecore, and it is not necessary to remove the tongue portion for thepurpose of collapsing the core.

Other modifications are possible within the scope of my invention asdefined in the appended claims, and the invention may be applied tocollapsible tire forms other than the specific type illustrated.

I claim:

1. A collapsible tire-building core structure comprising a segmentalcore including core segments, one of which is hinged to swing saidsegments outward, transversely of the normal core plane, and apair ofsegmen-ts hinged to the first-said segment, said segments having outerbody portions made of a metal of the aluminum group to decrease theweight and provide low moments of in ertia centered toward the hingeaxes, and inner tongue portions carrying the hinge members and made of aheavy and strong metal, a key segment fitted between the ends of saidpair of segments, and a rotary chuck slidingly supporting said keysegment and hinged to the first-said core segment.

2. A collapsible tire-building form composed of segments each comprisingan outer body portion made of relatively light metal and cast upon aninner portion made of relatively heavy and strong metal which haslongitudinally-spaced anchor lugs interlocking withthe metal of the bodyportion.

collapsible tire-building; core composed of segments each comprlsmg aninner tongueportion made of relatively heavy and.

strong metal and an outer body portion cast thereon and made ofrelatively light metal the-tongue portion being formed with anchor lugsembedded in the body portion and with. an undercut groove between saidlugs for receiving an interlocking Web of the metal of said bodyportion.

In Witness whereof I have hereuntoset' my hand this 3d day ofJune,.1929.

FREEMAN De MASON.

